The missing track error usually happens when you want to listen to or sync a particular song.
There are a few things you can try to solve this issue:
Firstly, if you are on desktop, we would always recommend to use Google Chrome on desktop
If you are using our website, try refreshing the page a few times.
It can also be useful to try to clear cache and browsing history
Both for app and website, try to disconnect your audio source and reconnect it via the Musixmatch Studio settings on the web or mobile app. Here is how.
If you are contributing to the song, please remember that you need Spotify Premium.
It can also be that the release is missing
If you are the artist of the song, you can add it yourself. Here is how.
If you are not the artist, please report the issue to the Slack Community in the channel called "catalogue-issues"